1. Field of the Invention
The present invention is generally directed to cable television. More particularly, the present invention is directed to transmission and detection of video, voice, and data signals over a cable-television network.
2. Background Art
A cable modem is typically configured to concurrently receive several different types of signals over a single coaxial cable. For example, a cable modem may concurrently receive television signals, voice signals, and data signals. To enable a customer to concurrently access the information provided by the different signals, a customer system typically includes software and/or firmware modules specially designed to process the different signals. For example, a customer system may include one or more modules to process Internet protocol-based (IP-based) television signals, one or more modules to process voice signals, and one or more modules to process data signals. Alternatively, the cable modem may pass video-based television signals directly to a set-top box. In either case, a customer can typically watch television, talk on the telephone, and surf the Internet—all at the same time.
To prevent a customer from accessing cable-services content (e.g., premium channels) without proper authorization, cable-service providers have historically used cable traps. A cable trap is a type of filter. Specifically, cable traps are configured to block the transmission of one or more cable channels (e.g., frequencies). If a cable trap is properly installed at a location (e.g., a tap) between a cable head-end and a cable modem at the customer location, the delivery of one or more channels into the customer's cable modem is blocked, thereby preventing the customer from receiving services for which he has not paid. Although modern cable systems now often use digital set-top box technologies to control the delivery of service to customers, cable traps continue to be used for customers who subscribe to only basic cable or cable-modem services in order to block extended basic services.
Unfortunately, cable traps are a physical-security mechanism and, as such, are less secure than digital set-top box technologies. In particular, cable traps are subject to alteration, especially removal, in order to enable reception of unauthorized services. Due to this susceptibility, a typical cable company regularly audits its facilities to ensure that cable traps remain in place where they belong.
However, conventional cable-trap audits are problematic for several reasons. As an initial matter, these audits typically involve manual inspection—an expensive and time-consuming process. Moreover, these audits can be ineffective in certain situations (e.g., when advanced notice is required before inspection). Such situations may arise, for example, in the context of multi-dwelling unit (MDU) buildings. In MDU buildings, cable traps are usually located in a utility closet. Often, advanced notice must be given to the building's superintendent before accessing the utility closet. However, even if a cable trap had been removed and/or tampered with, the advanced notice provides the opportunity for the cable trap to be re-installed and/or replaced before the inspection occurs.
Given the foregoing, what is needed is automatic detection of cable traps and applications thereof.